Williams RE, Bosnic N, Sweeney CT, Duncan AW, Levine KB, Brogan M, Cook SF. Prevalence of opioid dispensings and concurrent gastrointestinal medications in Quebec. Pain Res Manag. 2008;13(5):395-400.
Manga N, Duffy JC, Rowe PH, Cronin MTD. A hierarchical QSAR model for urinary excretion of drugs in humans as a predictive tool for biotransformation. QSAR Comb Sci. 2003 Apr 17;22(2):263-73. doi: 10.1002/qsar.200390021